[win32] Register internal ZoomChange listener for monitor specific scaling

As the DPI change behavior in the windows implementation is fully
using the ZoomChange event now, it must be ensured, that the internal
ZoomChange listener, that adapt the Wigets for monitor specific scaling
must be be registered in this case.

Author: akoch-yatta

bundles/org.eclipse.swt/Eclipse SWT Tests/win32/org/eclipse/swt/widgets/ControlWin32Tests.java

@@ -58,15 +58,15 @@ public void testSetFontWithMonitorSpecificScalingEnabled() {
 	}
 
 	@Test
-	public void testScaleFontCorrectlyInNoAutoScaleScenario() {
+	public void testDoNotScaleFontInNoAutoScaleScenario() {
 		Win32DPIUtils.setMonitorSpecificScaling(false);
 		Display display = Display.getDefault();
 
 		assertFalse("Autoscale property is not set to false", display.isRescalingAtRuntime());
 		int scalingFactor = 2;
 		FontComparison fontComparison = updateFont(scalingFactor);
-		assertEquals("Font height in pixels is not adjusted according to the scale factor",
-				fontComparison.originalFontHeight * scalingFactor, fontComparison.currentFontHeight);
+		assertEquals("Font height in pixels is different when setting the same font again",
+				fontComparison.originalFontHeight, fontComparison.currentFontHeight);
 	}
 
 	@Test

bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Widget.java

@@ -194,10 +194,12 @@ public Widget (Widget parent, int style) {
 }
 
 void registerDPIChangeListener() {
-	this.addListener(SWT.ZoomChanged, event -> {
-		float scalingFactor = 1f * DPIUtil.getZoomForAutoscaleProperty(event.detail) / DPIUtil.getZoomForAutoscaleProperty(nativeZoom);
-		handleDPIChange(event, scalingFactor);
-	});
+	if (display.isRescalingAtRuntime()) {
+		this.addListener(SWT.ZoomChanged, event -> {
+			float scalingFactor = 1f * DPIUtil.getZoomForAutoscaleProperty(event.detail) / DPIUtil.getZoomForAutoscaleProperty(nativeZoom);
+			handleDPIChange(event, scalingFactor);
+		});
+	}
 }
 
 void _addListener (int eventType, Listener listener) {